Mast for conveyer vehicles



May 22, 1962 H. MEHLMANN MAST FOR CONVEYER VEHICLES 2 Sheets-Sheet 2 Filed Dec. 5, 1960 HANS MEHLMAN/V United States Patent 3,035,663 MAST FOR CONVEYER VEHICLES Hans Mehlmann, Westhoven-Porz, near Koln, Germany,

The present invention relates to a mast for conveyer vehicles such as especially lifting trucks and more particularly to the mast of the type having a fixed interior member and the slidable exterior member concentrically disposed about the interior member and vertically slidable relative to the latter.

It is known to provide conveyer vehicles with a central mast of the aforementioned type and wherein the exterior member is slidably guided on the interior by means of various rolls spaced at three different levels, for example a lower level, an intermediate level and an upper level. The axes of these rolls are positioned vertically on the main symmetrical plane of the mast extending through the load to be lifted and the respective axes of one pair of these rolls are positioned in a plane extending vertically relative to the longitudinal axis of the mast. In addition to the aforementioned rolls positioned at the interior mast member there are provided exterior rolls the respective axes of which extend parallel to the respective axes of the interior rolls. The interior rolls are so dimensioned that one or the other of an interior runway surface of the exterior mast member is in running contact with the rolls. As a consequence, the diameter of these rolls must be somewhat smaller than the distance between two oppositely disposed runway surfaces. This play, as well as the inevitable wear, results in a very imperfect guide of the displaceable mast member. It has already been suggested to provide additional rolls the axes of which are positioned vertically relative to the axes of the other rolls and relative to the longitudinal axis of the mast and which are supposed to effect a lateral guiding of the mast member. Again, some play must be provided in order to enable some rotation of the guide mast member about the lifting axis. The lateral stability of these guide rolls and the lifting carriage is unsatisfactory.

With the foregoing in mind it is the object of the present invention to provide a mast for conveyor vehicles and particularly lifting trucks of the type having a fixed interior member and a vertically slidable exterior member, which is provided with guide means for the aforementioned members and the lifting carriage, that affords excellent stability and a very good guide effect without undesirable and unnecessary play and increasing inaccurate guiding effect due to wear.

These and other objects of the invention are achieved by the mast of the present invention comprising an exterior tubular elongated member, vertically slidably, concentrically positioned about an interior member and a lifting carriage vertically slidably positioned on the exterior member, a pluralityof guide rolls positioned at three diiferent levels at the interior mast member for guiding the exterior mast member, and a plurality of rolls at two different levels on the lifting carriage for guiding the same relative to the exterior member. According to the invention, the plurality of rolls at the interior member comprises two pairs of rolls at a lower portion, two pairs of rolls at an intermediate portion and one pair of rolls at an upper portion, all of which rolls are positioned at eccentric bearing bolts and running on runways provided at the interior surface of the exterior mast member. has two outwardly projecting ledge portions at opposite ends. Each of these ledge portions has two runway surfaces, each forming an acute angle with the central plane of the mast not extending through the load to be lifted. The lifting carriage supports rolls positioned with their running surfaces in the same manner as the aforementioned runways on the ledges, so that therolls run' with substantially their entire peripheral surface along the runways on the ledges.

According to a preferred embodiment of the invention both members forming the mast consist of tubular members of rectangular and preferably square cross-section and the rolls are so positioned that their respective axes; run parallel to the lifting plane and vertically relative to' the lifting direction of the lifting carriage.

According to another embodiment of the invention a greater lateral rigidity is obtained by so constructing the mast that its extension in the plane parallel to the direction of movement of the lifting carriage not going through the load to be lifted is far greater than its extension in direction of the plane through the load. According to this embodiment of the invention, the mast has a fixed mast member composed of two columns spaced at a comparatively great distance and connected with each other by a transverse frame structure. Furthermore, the mast has a displaceable mast member consisting of two edge portions which are also connected with each other by a transverse frame structure. The broad sides of both the fixed and the displaceable members are substantially greater than their respective small sides.

Further advantageous features of the invention will'be apparent from the detail description of the drawings,

wherein- FIGURE 1 is a side elevational view, partly in section, of the mast according to the invention;

FIGURE 2 is a w'ew of the lower part of the mast ing the interior rolls and the bearings therefor, somewhatenlarged.

Turning first to FIGURE 1, the lifting carriage 20 shown in its highest possible position on the mast. The mast comprises an interior, fixed tubular, elongated member 3 pivotally positioned on a suitable eonveyer vehicle such as a lifting truck, not shown, as at 1 and 2.

As shown particularly in FIGURE 3, the interior member 3 has a rectangular and preferably square crosssection. Disposed about the interior member 3 is the exterior mast member 13, which is also a tubular, elongated member with rectangular and preferably square crossrolls slightly projects beyond the exterior edges of interior member 3 so as to contact the runway surfaces atthe walls of exterior mast member 13 so that the exterior. member is displaceably guided on the interior member. The rolls 7 through 10 are positioned on eccentric bearing bolts 25, 26, 27, 28, for example,with intermediate roller Patented May 22, 1962,

Furthermore, the exterior mast member 1 ing the two U'-shaped elements. 7

According to another embodiment of the invention,

bearings 29 or slide bearings 30. The eccentric bearing bolts each have a slot 31 enabling adjustment of their eccentricity. A threaded ring 32 is provided for securing the eccentric bolts in their respective positions. Due to this adjustability the exterior mast member 13 is displaceable relative to the interior member substantially without any play and any slack movement about its longitudinal axis. The exterior member 13- is guided at the interior member 3 in a plane 33 extending vertically relative to direction 24 by means of glide rails 34, 35, pref erably from a plastic material.

Preferably, the load rolls in the lower plane 4 are positioned above the lowermost end of the mast by a distance in the range from 60 to 120 centimeters. Furthermore, a security butting face 21 is provided at the interior memher 3 in the upper level 6. This will alford a better support for the exterior member during acceleration of the speed of the vehicle. Another such safety butting face 22 is provided at the interior member in its lowermost portion. This provides a protection against shocks in the lowermost position of the exterior member 13, as such shocks are transmitted directly from the lifting carriage to the pivoting point 2.

The exterior mast member 13 has ledge portions 14, at opposite sides forming obliquely disposed running surfaces 36, 37, 38 md 39. These surfaces each form an acute angle with the axial plane passing through the Center of each ledge portion 14, 15 and the center of the mast, and these surfaces are in contact with the running surfaces of rolls 16, 17 and 18, 19, positioned on lifting carriage 20. These rolls are so positioned that their peripheral surfaces run substantially entirely on the runways. In other words, the rolls are disposed obliquely relative to one another and relative to the main symmetn'cal planes of the mast. The lifting carriage is thus self-centering and all occurring forces are transmitted from lifting carriage 20 to the exterior mast member 13 in such a manner that the lifting carriage 20 always retains its accurate position. 7

According to further advantageous features of the invention, the rolls 7, 8, 9 and 10 are preferably positioned as illustrated in FIGURE 5. It will be seen that the interior member 3 is reinforcd at the location of the rolls by a plate member 40 having borings 41 and 42 for re ceiving the bearing bolts and 27, as well as recesses 43 and 44 for the rolls 7 and 9. The rolls 7 and19 are positioned at the runways 47, 48, eccentrically positioned relative to bolts 45, 46. The recesses 43 and 44 form the greasing chambers and are covered by resilient scraping and sealing sheets 49 and 50, scraping the grease carried by the rolls. The sheets 49 and 50 also secure the threaded rings 32 in position.

As will be seen in FIGURE 2, the exterior mast member 13 has a slot 51 at its lower end. This will enable the exterior member 13 to be lowered beyond the pivoting point I of the interior member 3. A weakening of strength as may be caused by slot 51 can be compensated by reinforcing bulged portions 52 of the exterior member, as illustrated in FIGURE 3.

As will be seen in FIGURE 3, the interior member 3 can be composed of two U-shaped elements, which thus form'a rectangular profile. The exterior member 13 can be assembled of two U-shaped elements having reinforcing bulged corners 52 and the projecting portions forming the ledgese 14, 15 as well as two plates 53, 54 connectillustrated in FIGURE 4, the interior mast member comprises support columns which are composed of two bars 61 and a connecting rod 62 connecting the two bars 61,

so as to form two interconnected support columns. These columns are connected at determined intervals by sheets 63 having downwardly bent flanges 64 connected with has a circular recess 66 through which there projects a hydraulic cylinder 7a whose lower end is connected with the fixed interior mast member, whereas the plunger 84, forming the piston means of this cylinder, is connected with the displaceable mast member. The latter is formed of two edge portions each consisting of a Y-shaped extruded member 68. The members 68 are connected with each other by sheets 69 and angle irons 70. The bars 62 support rolls 71a and 71b, positioned on eccentric bearing bolts 72 by means of slide bearings 73 or roller bearings 74. The eccentric bolts 72 have slots 76 allowing for an adjustment of their respective eccentricity and are securable in their adjusted positions by means of threaded rings 75. The sheets 77 secure the threaded rings 75 and, at the same time, cover the recesses receiving the rolls 71a and 7112, so as to form greasing chambers beyond which there project only the running surfaces of rolls 71a and 71b. Glide rails 78 are provided in order to afford a guide in case of lateral displacement of the exterior mast portion relative to the interior mast portion. Since such lateral displacements occur only under the influence of very small forces, the wear of the glide rails 78 is insignificant. The rolls 71a and 71b roll on runways formed by the interior sides of the branches of Y-shaped members 68. The Y-shaped members also have portions 79 each having two runway surfaces 80, each forming a steep angle with the central plane of the mast. Rolls 81, mounted on lifting carriage 82 and positioned with the same steep angles as runway surfaces 80, run on the latter.

It will be appreciated that the mast as shown in the drawings is interrupted at 83, Whereas in reality it continues.

The bearing bolts 72 are adjustable with respect to their eccentricity and, consequently, the position of the rolls 71a and 71b can always be so adjusted that their peripheral surfaces contact the associated runwaysurfaces. As a result, the displaceable mast portion is guided relative to the fixed mast portion substantially without play even with masts of comparatively great diameter. The oblique position of the runway surfaces '80 assures a self-adjustment of the rolls 81 on the surface 20 so as to effect a satisfactory travel of the rolls.

It will be understood that this invention is susceptible to modifications in order to adapt it to different usages and conditions and, accordingly, it is desired to comprehend such modifications within this invention as may fall 7 said lower portion of said interior member, two pairs of lower rolls in said lower portion on said lower bearing bolts, a plurality of eccentric intermediate bearing bolts in said intermediate portion of said interior member, two pairs of intermediate rolls in said intermediate portion on said intermediate bearing bolts, a plurality of eccentric upper bearing bolts, one pair of upp r rolls in said upper portion on said upper bearing bolts, a first and a second outwardly projecting ledge. portion at opposite ends of said exterior member, each of said portions having a first and a second runway surface at op-.

, posite sides each forming an acuate angle with'the axial the two bars 61 forming one column. Also connected with the: bar 61 are bridge portions '65. The sheet 63 plane/passing through. the center of each ledge portion and the center of the mast, and two pairs of exterior rolls 2. A mast for conveyor vehicles according to claim 1, with a safety butting surface in the upper portion at said interior member opposite said upper rolls.

3. A mast for conveyer vehicles according to claim 1, with a safety butting surface in the lower portion at said interior member.

4. A mast for conveyer vehicles according to claim 1, with said lower rolls being positioned above the lowermost end of said interior member by a distance in the range from 60 to 120 centimeters.

5. A mast for conveyer vehicles according to claim 1, said interior member and said exterior member having rectangular cross-sections and said lower, intermediate and upper rolls having axes running vertically relative to the direction of movement of said lifting carriage and parallel relative to the plane of movement of said lifting carriage.

6. A mast for conveyer vehicles according to claim 1, with a plurality of recesses in said interior member receiving said lower, intermediate, and upper rolls and each forming a greasing chamber, and means for adjusting the eccentricity of said bearing bolts.

7. A mast for conveyor vehicles according to claim 6, with a plurality of sealing and scraping sheets covering said recesses forming said greasing chambers, a plurality of threaded rings retaining said eccentric bearing bolts in position.

8. A mast for conveyer vehicles according to claim 1, said interior member consisting of two assembled U- shaped members.

9. A mast for conveyer vehicles according to claim 1, said exterior member consisting of two U-shaped members having reinforced bulged corners and two plates connecting said U-shaped members with each other.

10. A mast for conveyer vehicles according to claim 1, said exterior member consisting of two widely spaced columns, a transverse frame structure connecting said columns with each other, and said interior member consisting of two edge portions, and a further transverse frame structure connecting said edge portions with each other, said exterior and said interior members each having a broad side and a small side, with the broad side being considerably greater than the small side.

11. A mast for conveyer vehicles according to claim 10, with said edge portions having a Y-shaped crosssection.

References Cited in the file of this patent UNITED STATES PATENTS 

